package mi.payment.utils;

import android.util.Base64;

import java.security.Key;
import java.security.spec.AlgorithmParameterSpec;

import javax.crypto.Cipher;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESKeySpec;
import javax.crypto.spec.IvParameterSpec;

import mi.payment.BuildConfig;
import mi.payment.constants.Configs;

public class DesUtils {

    private static final String ALGORITHM_DES = "DES/CBC/PKCS5Padding";

    /**
     * DES算法，加密
     *
     * @param data 待加密字符串
     * @param key  加密私钥，长度不能够小于8位
     * @return 加密后的字节数组，一般结合Base64编码使用
     * @throws Exception 异常
     */
    public static String encode(String key, String data) throws Exception {
        byte[] dataBytes = data.getBytes();
        return encode(key, dataBytes);
    }

    /**
     * DES算法，加密
     *
     * @param data 待加密字符串
     * @param key  加密私钥，长度不能够小于8位
     * @return 加密后的字节数组，一般结合Base64编码使用
     * @throws Exception 异常
     */
    private static String encode(String key, byte[] data) throws Exception {
        byte[] keyBytes = key.getBytes();
        DESKeySpec dks = new DESKeySpec(keyBytes);
        SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");
        Key secretKey = keyFactory.generateSecret(dks);
        Cipher cipher = Cipher.getInstance(ALGORITHM_DES);
        byte[] viBytes = Configs.DES_VI.getBytes();
        AlgorithmParameterSpec paramSpec = new IvParameterSpec(viBytes);
        cipher.init(Cipher.ENCRYPT_MODE, secretKey, paramSpec);
        byte[] bytes = cipher.doFinal(data);
        return Base64.encodeToString(bytes, 0);
    }

    /**
     * DES算法，解密
     *
     * @param data 待解密字符串
     * @param key  解密私钥，长度不能够小于8位
     * @return 解密后的字节数组
     * @throws Exception 异常
     */
    private static byte[] decode(String key, byte[] data) throws Exception {
        byte[] keyBytes = key.getBytes();
        DESKeySpec dks = new DESKeySpec(keyBytes);
        SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");
        Key secretKey = keyFactory.generateSecret(dks);
        Cipher cipher = Cipher.getInstance(ALGORITHM_DES);
        byte[] viBytes = Configs.DES_VI.getBytes();
        AlgorithmParameterSpec paramSpec = new IvParameterSpec(viBytes);
        cipher.init(Cipher.DECRYPT_MODE, secretKey, paramSpec);
        return cipher.doFinal(data);
    }


}